I'd heard an interesting story while trying to get into Magical Girl Raising Project. Apparently, when the series was still in the public eye back around 2016-17 or so, it was discovered the guy who was doing translations at the time (PlatFleece I believe his name was) was actually incompetent at Japanese and making shit up as he went along (deleting or adding entire paragraphs for example), and everyone had fallen for it for like a year or so since nobody had bothered to get raws themselves and those that did and called Plat out were damage-controlled by a cocksucker cadre cultivated on Dicksword. The inability to verify until an entire retranslation of all the books up to that point was done played a large factor in the series falling into obscurity among Western circles, or so the story goes.
It was interesting to me because far as I knew at the time, bullshit TL stuff was done either by failed writers in official companies or agenda-driven cucks on Reddit and other such malcontent sites -- it kind of slipped my mind that autists could fuck up efforts for entirely separate reasons, like their own pride. That made me curious: What other examples of translation fuckery have you noticed in fan TL?